Nasal Trigeminal Perception of Two Representative Microbial Volatile Organic Compounds (MVOCs): 1-Octen-3-ol and 3-Octanol—a Pilot Study

Nasal symptoms can be associated with indoor mold overgrowth, even absent allergic sensitization. An alternative pathogenic mechanism—mucous membrane irritation by microbial volatile organic compounds (MVOCs)—has been proposed. We conducted a pilot human study of nasal irritation by two MVOCs, 1-octen-3-ol and 3-octanol, hypothesizing that the former would show greater irritant potency based upon the compounds’ relative irritant potencies in rodents.

Serial dilutions of the test compounds were prepared in odorless mineral oil vehicle, with headspace vapor concentrations documented by gas chromatography. Eight-step dilution series (with ascending concentration ratios ~?1.34) were prepared. A nasal lateralization protocol was utilized. Ten subjects (seven females), aged 23–69, were each tested on four separate days, with each test compound being presented twice in alternating/counterbalanced order over the four testing days. Individual lateralization thresholds for a given compound, taken as dilution step, were averaged across subjects.

Eight subjects were reliably able to lateralize stimuli for one or both test compounds. Among the 32 testing sessions completed by these eight subjects, 1-octen-3-ol was successfully lateralized in 15/16 and 3-octanol in 11/16. The mean dilution step at threshold was 3.125 for 1-octen-3-ol and 2.58 for 3-octanol.

When presented as brief (~?4?s.) stimuli, high concentrations of identified MVOCs can act as nasal mucosal irritants. Both detectability and repeatability, but not absolute (ppm) thresholds, exhibited compound-specific trends consistent with animal experimental data. Studies involving more protracted exposures with larger sample sizes may yield more realistic irritant threshold estimates.

At sufficiently high concentrations, MVOCs can produce nasal irritation in humans.